SKIN COLLAGEN AND THICKNESS IN ACROMEGALY AND HYPOPITUITARISM

The thickness of the forearm skin and its collagen content and density were measured in a group of patients with acromegaly and hypopituitarism. In acromegaly the total content, thickness and collagen density were all increased. There was a smaller and less consistent increase in percentage collagen content. In hypopituitarism total skin collagen and thickness were both decreased and collagen density and percentage collagen content remained normal.     

Collagen Fiber Formation in Repair Tissue: Development of Strength and Toughness

Dermal repair tissue shows a progressive increase in collagen content which may be related to the wound tensile strength. Wound strength and extensibility are lower than those found in normal skin. In animals, wounds closed by metal clips are chosen as a model to study the proliferative and remodeling phases of healing from a mechanical and morphological point of view. During the proliferative phase the low wound strength is associated with formation of collagen fibers of small diameter, later, (days 28–45) an acute change appears corresponding to the remodeling phase, with 1) increased collagen fiber diameters observed by scanning electron microscopy and light microscopy, and 2) increased tensile strength and toughness. By 180 days, wound strength and collagen fiber morphology were close to that observed in the normal skin. These observations show a direct relationship between collagen fiber diameter and tensile strength. In addition, packing density of collagen fibrils (determined by the birefringence retardation per unit thickness under polarized light) was unchanged until day 90, although collagen fiber diameters increased during this time.     

SERUM T3 AND T4 LEVELS IN PATIENTS WITH ANOREXIA NERVOSA SHOWING TRANSIENT HYPERTHYROIDISM DURING WEIGHT GAIN

Serum thyroxine (T4) and triiodothyronine (T3) levels were measured in a group of thirty-three patients with anorexia nervosa (AN) and compared with twenty-five control women presenting with hirsutism and twenty-one patients with primary myxoedema. T3 levels in the AN patients were significantly lower than in the control subjects and in the patients with myxoedema while T4 levels were significantly higher than in the patients with hypothyroidism but significantly lower than in the control group. Seventeen anorexia patients had further T3 and T4 levels measured following an arbitrary 25% weight gain and both levels had increased significantly. For individual patients, the absolute rise in T3 levels was significantly correlated with the rate of weight gain. Thirteen patients had serial T3 and T4 levels measured during their periods of weight gain. Eight of these subjects showed a gradual rise in T3 levels from subnormal or low normal levels to values in the upper normal range. Four subjects showed a distinct and self limiting overshoot of T3 levels and, associated with this, the patients had clinical features of mild hyperthyroidism.     

Investigation on the effects of experimental STZ-induced diabetic rat model on basal membrane structures and gap junctions of skin

This study was designed to determine the impairment of the skin structure in experimentally-induced diabetes with injection of streptozotocin (STZ). Experimental groups consisted of controls (group 1, N?=?10) and diabetes groups (group 2, N?=?10). Dorsal skin was removed for routine histological tissue procedures. Hematoxylene and Eosin (HE), Masson’s Trichrome and Periodic Acid Schiff (PAS) stainings, immunohistochemical connexin 43 (Cx43) and type IV collagen stainings were applied. Morphometry of epidermal thickness were also determined. Group 2 revealed decrease in epidermal thickness with disintegration of epithelium and decrease of dermal collagen fibers. Stratum spinosum were morphologically abnormal for group 2. Measurements of epidermal thickness revealed statistically significant decrease (P?=?0.000). PAS staining for group 2 revealed disruption of the basement membrane. Epithelial scar formation, deterioration of transformation in the polyhedral cells, degradation of epidermis and decrease in PAS staining for vascular structures were observed, whereas the reticular dermis and hair follicles were normal. Collagen fiber density in group 2 were found to be prominently decreased in dermis with Masson’s Trichrome staining. Evident decrease in immunostaining of Cx43 and type IV collagen were also shown in diabetic group in comparison to the controls. In conclusion, diabetes not only induced impairment of the epidermal integrity and deterioration in the epidermis via loss of gap junctions (the most prominent cellular junctional complex), but also caused dramatically negative impact on the dermal collagen content, and integrity of the basement membrane.     

ASSESSMENT OF BODY COMPOSITION IN NORMAL AND OBESE SUBJECTS

SUMMARY Multiple anthropometric measurements, which included those of weight, height, skinfold thickness, bone diameters and limb circumferences, together with estimations of creatinine excretion, were performed on 52 male and 42 female healthy subjects, both obese and of normal weight. Fat mass was estimated from two equations, which had been derived by previous workers from measurements of body density, and combined total body water content and body density. One was based on weight and skeletal measurements, and the other on the iliac crest circumference and triceps skinfold thickness. It was shown that there was close agreement between these two estimates, even in very obese subjects, thus extending the observations made by the original authors. When the mean of these two values was used as the reference value for fat mass, it was found that the latter could be simply predicted in both sexes from weight/height² and percentage ideal weight calculations and in males from iliac crest circumference. The error of prediction was less than 6·8 kg. (twice the S.D.). Prediction was better (error less than 5·2 kg.) in both sexes using both weight/height² and the iliac crest circumference. Skinfold thicknesses were of less value in predicting fat mass. These conclusions only apply to Western populations of this type of body build, in whom fat is almost exclusively responsible for variations in bulk. In interracial studies, skin fold measurements may give a better estimate of relative obesity. With creatinine excretion as our index of muscle mass, we found that no body measurement was of value in estimating muscularity. The best parameter was fat-free weight, but this was of poor value, especially in obese males. It emphasizes that muscle forms a very variable proportion of fat-free weight. To obtain a reliable estimate of muscularity in population studies it appears essential to estimate creatinine excretion.     

Collagenous abnormalities in the heart of the tight-skin mouse

The tight-skin (TSK) mouse, a possible animal model for scleroderma, has multiple abnormalities including increased dermal thickness, cardiomegaly, emphysematous lungs, and an enlarged skeleton. Previous investigations have demonstrated an increased collagen and glycosaminoglycan (GAG) content in the skin and lungs of these mice. The present correlative investigation of the biochemical and ultrastructural properties of the heart in the TSK mouse also revealed an increased presence of collagen. Analysis of collagen types in the TSK heart showed there was a shift in the ratio of type I: type III: type V from the normal values. Over 90% of the collagen was type I, while both types III and V were decreased in this organ. The ultrastructural examination of the left ventricle demonstrated extensive accumulations of perivascular and intercellular edema fluid, foci of myocytolysis, and areas of moderately increased collagen deposits within interstitial sites. These findings suggest that an increased collagen deposition (type 1) may be a contributing factor to cardiac enlargement in the TSK mouse.     

SPINAL BONE MINERAL CONTENT IN MYXOEDEMA AND THYROTOXICOSIS. EFFECTS OF THYROID HORMONE(S) AND ANTITHYROID TREATMENT

The effects of thyroid hormones and antithyroid treatment upon lumbar spine bone mineral content (lumbar BMC) were studied in a consecutive series of patients with myxoedema and thyrotoxicosis, respectively. All patients were investigated in the untreated state and 3-monthly during appropriate treatment for 1 year by using dual-photon [153Gd] absorptiometry. Patients with myxoedema (n = 8) did not differ from normal individuals as regards initial lumbar BMC, but levothyroxine-treatment caused significant reduction in this variable. The median decrease in lumbar BMC after 1 year was 8.9% (95% confidence limits 1.5-15.4%, P less than 0.05). This loss of bone might be attributed to an inappropriate increase in bone turnover in the euthyroid state. It is as yet uncertain whether it predisposes to spinal osteopenia. Median lumbar BMC in patients with thyrotoxicosis (n = 25) was 12.6% (2.0-16.6%, P less than 0.05) lower than that of normal individuals before the beginning of treatment. Lumbar BMC increased during antithyroid therapy. The median gain in bone mineral after 1 year was 3.7% (1.6-9.6%, P less than 0.01). These findings suggest that excess of thyroid hormones leads to negative spinal bone mineral balance. The revealed bone loss was clinically insignificant, however, and it appeared to be at least partially reversible after antithyroid treatment.     

METABOLIC RESPONSES TO MONOCOMPONENT HUMAN INSULIN INFUSIONS IN NORMAL SUBJECTS AND PATIENTS WITH LIVER AND ENDOCRINE DISEASE

Hypoglycaemic and growth hormone responses were studied at different steady-state plasma insulin concentrations during a graded infusion of monocomponent human insulin. The control group consisted of ten volunteer subjects. The other groups studied included women taking oral contraceptives and patients with obesity, thyrotoxicosis, myxoedema, acromegaly, diabetes mellitus (moderate and severe) and liver disease. The hypoglycaemic response was measured in two ways: (i) the percentage reduction in plasma glucose below basal, and (ii) the rate of fall of plasma glucose (K_g-%/min). Insulin sensitivity was greatest in the normal subjects and in the other groups decreased in the order thyrotoxicosis>oral contraceptive>obesity>myxoedema>acromegaly>liver disease. Insulin sensitivity was difficult to assess in the diabetic patients because basal plasma glucose concentrations were elevated. At any given insulin concentration, the diabetics metabolized approximately the same amount of glucose as the normal subjects but the fact that this rate of glucose turnover occurred at higher plasma glucose concentrations probably indicated insulin resistance. Within each group K_g at each dose level of insulin correlated with the steady state plasma insulin concentration during the same infusion period. Diminishing sensitivity to insulin was reflected in an increasing fasting plasma insulin and insulin/glucose ratio except in patients with diabetes. GH responses to insulin infusion in normal subjects reflected the pattern of fall of plasma glucose. In the diabetic patients GH secretion appeared to be related to the infusion of insulin and occurred before plasma glucose had fallen to hypoglycaemic levels. GH secretory patterns were within normal limits in women taking oral contraceptives and in seven of eleven patients with liver disease but were impaired in three of seven patients with thyrotoxicosis and four of five patients with myxoedema. Four obese patients had a markedly delayed but eventually normal GH response.     

Composition of coronary atherosclerotic plaque in the intima and media affects intravascular ultrasound measurements of intimal thickness

Objectives. The purpose of this study was to evaluate how intravascular ultrasound-determined thickness and reflectivity of the inner echogenic layer of coronary artery plaque is affected by changes in collagen, elastin, proteoglycan, calcium and lipid content in the intima and media.Background. Coronary artery plaque often results in disruption of the internal elastic lamina and in increased collagen in the media as well as increased intimal lipid, calcium and proteoglycan content. How these factors affect intravascular ultrasound-derived measurements of intimal thickness are unknown.Methods. Twenty-one coronary artery segments from 10 patients with varying degrees of coronary artery disease were obtained fresh and unfixed at autopsy. Instravascular ultrasound (30-MHz, 3.5F catheter) was performed at regions in the vessel where a three-layered region was evident. Quantitative measurements of inner echogenic and deeper echolucent layer thickness were determined as well as estimates of ultrasound reflectivity and compared with histologic measurments of intimal and medial thickness and collagen, proteoglycan, lipid and calcium content.Results. In plaque >300 μm thick and equivalent histologic levels of collagen, inner echogenic layer reflectivity was greater in regions with a greater amount of calcium and proteoglycan and lesser amounts of lipid. Inner echogenic layer thickness correlated well with intimal thickness but had the best correlation with intimal and medial thickness when medial collagen content was increased (r = 0.89). The median observed difference between intimal and inner echogenic thickness was 160 (p < 0.05 compared with zero), whereas the median observed difference between inner echogenic thickness and intimal plus medial thickness when medial collagen content was increased was 60 (not significantly different from zero).Conclusions. The inner echogenic layer of human coronary artery plaque may represent both intima and media. The echolucent layer by ultrasound may represent only the basal section of the media that does not contain high collagen contest.     

Age changes in collagen characteristics of bone and skin of a short-lived species of reptile.

Decalcified bone collagen of older male garden lizards, Calotes versicolor, was less susceptible to digestion by collagenase from Clostridium histolyticum than that from younger individuals. In aged skin the percentage solubility and the soluble/insoluble collagen ratio decreased, with a concomitant rise in insoluble and total collagen. Collagen/unit area increased with advancing age in both dorsal and ventral skin. These results from a non-mammalian poikilothermic vertebrate provide additional evidence in favour of the cross-linkage theory of ageing and suggest a common pattern of collagen ageing in vertebrates.     

Cardiac mast cell- and chymase-mediated matrix metalloproteinase activity and left ventricular remodeling in mitral regurgitation in the dog

The present study tested the hypothesis that cardiac mast cells and chymase are associated with matrix metalloproteinase (MMP) activation and extracellular matrix (ECM) degradation in the evolution of left ventricular (LV) chamber remodeling secondary to experimental mitral regurgitation (MR) in dogs. LV mast cell density, chymase activity, and angiotensin II (ANG II) levels were significantly increased 2 and 4 weeks post-MR, while an increase in angiotensin-converting enzyme (ACE) activity was not seen prior to the chronic 24 week stage. As early as 2 and 4 weeks, there was a significant decrease in interstitial myocardial collagen content that was associated with an increase in LV end-diastolic diameter (LVEDD) but a normal LVEDD/wall thickness ratio. While mast cell density decreased to normal at 24 weeks, both chymase and MMP-2 activity remained increased throughout the entire 24-week period post-MR. By 24 weeks a transition to an adverse pattern of LV remodeling characterized by a 2-fold increase in the LVEDD/wall thickness ratio had occurred. Thus, this study supports the hypothesis that mast cells and chymase are important modulators of MMP activity and ECM degradation, contributing to adverse LV remodeling in chronic volume overload secondary to MR.     

Low Density Lipoprotein Peptide Metabolism in Nephrotic Syndrome

Using human serum low density lipoprotein labelled in the peptide component with ¹³¹I or ¹²⁵I, turnover studies were carried out in nine patients suffering from nephrotic syndrome with accompanying hyperlipoproteinaemia. Results were compared with data obtained previously in a group of normal subjects, and with similar information from patients whose hyperlipoproteinaemia was associated with syndromes other than nephrosis. Fractional catabolic rates were normal in the nine patients with nephrotic syndrome and in four patients with diabetes mellitus and hyperlipoproteinaemia. This pattern was similar to that previously described for patients with two forms of primary familial hyperlipoproteinaemia, but differed from the pattern reported for myxoedema in which hyperlipoproteinaemia was associated with a reduced fractional catabolic rate for low density lipoprotein peptide. In hypothyroidism the absolute catabolic rate was within the range observed in normal people, whereas in nephrosis and in primary or familial hyperlipoproteinaemia there was an increase in absolute turnover although the fractional rates were normal. From analysis of plasma decay curves it was concluded that in nephrotic syndrome, and in myxoedema, the proportion of the total miscible low density lipoprotein pool lying outside the plasma compartment was reduced.     

ACID GLYCOSAMINOGLYCANS IN MYXOEDEMA

Acid glycosaminoglycans were measured in the tissues of a virtually untreated 83-year-old woman with myxoedema. Intercellular oedema was demonstrated histologically in the tongue, myocardium, striated muscles, and in the skin. Tissue oedema was absent in two female control patients. All tissues from the patient with myxoedema, apart from the stomach, showed high concentrations of hyaluronic acid, but there was no consistent elevation of chondroitin-4,6-sulphate, heparan sulphate or dermatan sulphate. The accumulation of hyaluronic acid might contribute to the oedema formation in myxoedema.     

Effects of chronic inhibition of converting enzyme on mechanical and structural properties of arteries in rat renovascular hypertension

The effect of hypertension and of therapy by converting enzyme inhibitor (S 9490-3, perindopril) on the function and structure of large arteries has been studied in two-kidney, one-clip Goldblatt hypertensive rats. After one month without treatment, clipped hypertensive rats (n = 24) and sham-operated rats (n = 24) were randomly allocated to treatment by S 9490, 1 mg/kg once a day (n = 24) or to placebo (n = 24) and pursued for 4 weeks. Hemodynamic parameters, including instantaneous pressure and aortic velocity measured by D?ppler, were recorded under anesthesia at the end of the treatment period. Passive mechanical properties of carotid arteries were recorded in situ in the presence or the absence of smooth muscle cell activity (potassium cyanide poisoning). Morphological parameters of the aortic media, including medial thickness, nucleus density, and cross sectional area and relative density in proteins of interstitial matrix, were recorded by an automated morphometrical system. Hypertension was associated with an increase in characteristic impedance of the aorta and a decrease in compliance of the arterial system. Treatment with converting enzyme inhibitors completely reversed these in vivo markers of the rigidity of large arteries. Hypertension was associated with a shift of the passive pressure-volume relation in the carotid. Treatment with converting enzyme inhibitors normalized the carotid pressure-volume relation, whereas poisoning smooth muscle cells induced a disappearance of the curve differences between hypertensive and normotensive animals. Morphometric analysis of aortic walls permits us to report this functional change to structural modification of the arterial wall. Aortic media thickness was increased by hypertension; this phenomenon was reversed by treatment. Modification of aortic thickness was due to hypertrophy of smooth muscle cells with parallel modifications of absolute amount of collagen, whereas absolute amount of elastin did not change in this early phase of renovascular hypertension in young rats. Treatment with converting enzyme inhibitors reversed the thickness of aortic media without regression of the increase in absolute amount of collagen content whereas absolute amount of elastin content did not change.     

Collagen content and types in the intestinal strictures of Crohn's disease

The collagen content and the relative amount of collagen types were quantitated in control intestine as well as in both inflamed and strictured intestine resected from patients with Crohn's disease. The major collagen type in control intestine was type I (68%), followed by types III (20%) and V (12%). In strictured intestine both collagen content and the relative amount of type V collagen were significantly increased compared with control intestine. Histologic studies demonstrated that in strictured specimens there was a striking proliferation of smooth muscle cells of the muscularis mucosae associated with an accumulation of collagen in the submucosa. The thickness of the muscularis propria was also increased. Immunohistochemical studies demonstrated small amounts of type V collagen in the submucosa of control bowel. In contrast, large amounts of type V collagen were seen in the fibrotic, expanded submucosa of strictured bowel, particularly in the areas where smooth muscle cells of the muscularis mucosae had proliferated. Intestinal strictures in Crohn's disease are therefore characterized by an accumulation of collagen, a proliferation of smooth muscle cells, and an increase in type V collagen, a collagen type produced in relatively large amounts by smooth muscle cells. These changes appear to result in both a loss of the normal compliance of the intestine and a thickening of the intestine wall, resulting ultimately in the intestinal obstruction so frequently seen in patients with Crohn's disease.     

Relative and absolute changes of activated platelets, microparticles and platelet aggregates after activation in vitro.

Standard flow cytometers provide relative numbers of activated platelets, microparticles, and platelet aggregates. With fluorescent beads it is now possible to determine absolute numbers. Whole blood and platelet-rich plasma were incubated with agonists (ADP, collagen, thrombin). CD62p expression, microparticle and platelet aggregate formation were measured. Flow-Count Fluorospheres((R)) were added to calculate absolute concentrations. After activation there was an increase in the percentage of CD62p-positive platelets. However, the total number of platelets decreased and therefore the absolute number of CD62p-positive platelets did not increase but decreased. The number of CD62p-positive platelets decreased not as much as the number of CD62p-negative platelets, which explains why the relative percentage of CD62p-positive platelets increased. A similar increase in percent and decrease in absolute counts was found for microparticles. Platelet aggregates increased both in relative and absolute numbers. These results suggest that the detection of activated platelets by flow cytometry has to be complemented by the determination of the absolute concentrations to avoid misinterpretation.     

Reduced strength of skin in Ehlers Danlos syndrome, type III

The biochemical properties, ratio collagen type I/type III and the pattern of reducible collagen crosslinks were studied in skin biopsy samples from 10 patients with Ehlers Danlos syndrome type III (ED III) and 10 age- and sex-matched controls. The ED III patients had marked reductions in skin strength and stiffness (42% and 22%, respectively). The ultimate extensibility of the skin, however, was not different from that of the controls. Consequently, a certain load applied to the skin of these patients results in greater deformation than in that of the controls, due to reduced stiffness. The bursting limit is no different from that of the controls. Thus the skin in the ED III patients is not hyperextensible, it merely has reduced strength and stiffness. The reduction in strength could not be explained by differences in skin thickness or collagen content. Skin thickness, collagen content and ratio collagen type I/type III were the same as in the controls, as also was the pattern of reducible collagen crosslinks. These alterations in the mechanical properties of the skin of patients with ED III may be attributable to the molecular structure of the mature collagen or the arrangement of the collagen fibres.     

Effects of intermittent parathyroid hormone administration on bone mineralization density in iliac crest biopsies from patients with osteoporosis: a paired study before and after treatment

Anabolic effects of PTH have been observed at several skeletal sites in humans by dual x-ray absorptiometry without differentiating between an actual increase in bone volume and an increase in mineral content within already established bone. The present study addressed this issue by evaluating the bone mineralization density distribution of iliac crest bone biopsies before and after PTH treatment for 18-36 months in men and women with osteoporosis using quantitative backscattered electron imaging. In cortical bone, pairwise comparison of the two biopsies before and after treatment revealed a reduction in the typical calcium concentration in men (-3.32%; P = 0.02, by paired t test), but no change in women, and the heterogeneity of mineralization increased in both males and females [+18.80% (P = 0.09) and +18.14% (P = 0.005), respectively]. In cancellous bone, there was no change in the typical calcium concentration, but there was a greater heterogeneity of mineralization in both men and women [+19.65% (P = 0.02) and +21.59% (P = 0.056), respectively] due to newly formed bone matrix. Small angle x-ray scattering performed on a subgroup of subjects revealed normal collagen/mineral structure. The findings confirm the observations that PTH stimulates skeletal remodeling, resulting in an increased percentage of newly formed bone matrix of lower mineral density.     

REDUCTION OF SKIN COLLAGEN WITH INCREASED SKIN THICKNESS IN POSTMENOPAUSAL WOMEN WITH RHEUMATOID ARTHRITIS

Thirty postmenopausal women with rheumatoid disease were investigatedwith skin biopsies and radiological measurements of skin thickness.When compared with menopausal-age-matched controls, the rheumatoidpatients had significantly reduced skin collagen content andincreased skin thickness. KEY WORDS: Skin, Rheumatoid arthritis, Postmenopausal